Initial version of a go version of the compiler wrapper.

Still calls the old wrapper if one of the following flags is given:
- Xclang-path
- clang-syntax
- env WITH_TIDY
- env FORCE_DISABLE_WERROR
- env GETRUSAGE
- env BISECT_STAGE

BUG=chromium:773875
TEST=Unit tests that also verify the produced command against the
TEST=existing compiler wrapper.

Change-Id: I1e0a720ce9f485d8015deefb2682f2cb760d82e4
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/toolchain-utils/+/1652057
Reviewed-by: Manoj Gupta <manojgupta@chromium.org>
Reviewed-by: Tobias Bosch <tbosch@google.com>
Reviewed-by: George Burgess <gbiv@chromium.org>
Tested-by: Tobias Bosch <tbosch@google.com>
Legacy-Commit-Queue: Commit Bot <commit-bot@chromium.org>

1 files changed, 60 insertions, 0 deletions

diff --git a/compiler_wrapper/ccache_flag.go b/compiler_wrapper/ccache_flag.go
new file mode 100644
index 00000000..13ee234d
--- /dev/null
+++ b/compiler_wrapper/ccache_flag.go
@@ -0,0 +1,60 @@
+package main
+
+func processCCacheFlag(sysroot string, builder *commandBuilder) {
+	// We should be able to share the objects across compilers as
+	// the pre-processed output will differ.  This allows boards
+	// that share compiler flags (like x86 boards) to share caches.
+	const ccacheDir = "/var/cache/distfiles/ccache"
+
+	useCCache := true
+	builder.transformArgs(func(arg builderArg) string {
+		if arg.Value == "-noccache" {
+			useCCache = false
+			return ""
+		}
+		return arg.Value
+	})
+
+	if useCCache {
+		// We need to get ccache to make relative paths from within the
+		// sysroot.  This lets us share cached files across boards (if
+		// all other things are equal of course like CFLAGS) as well as
+		// across versions.  A quick test is something like:
+		//   $ export CFLAGS='-O2 -g -pipe' CXXFLAGS='-O2 -g -pipe'
+		//   $ BOARD=x86-alex
+		//   $ cros_workon-$BOARD stop cros-disks
+		//   $ emerge-$BOARD cros-disks
+		//   $ cros_workon-$BOARD start cros-disks
+		//   $ emerge-$BOARD cros-disks
+		//   $ BOARD=amd64-generic
+		//   $ cros_workon-$BOARD stop cros-disks
+		//   $ emerge-$BOARD cros-disks
+		//   $ cros_workon-$BOARD start cros-disks
+		//   $ emerge-$BOARD cros-disks
+		// All of those will get cache hits (ignoring the first one
+		// which will seed the cache) due to this setting.
+		builder.updateEnv("CCACHE_BASEDIR=" + sysroot)
+		if builder.env.getenv("CCACHE_DISABLE") != "" {
+			// Portage likes to set this for us when it has FEATURES=-ccache.
+			// The other vars we need to setup manually because of tools like
+			// scons that scrubs the env before we get executed.
+			builder.updateEnv("CCACHE_DISABLE=")
+		}
+		// If RESTRICT=sandbox is enabled, then sandbox won't be setup,
+		// and the env vars won't be available for appending.
+		if sandboxRewrite := builder.env.getenv("SANDBOX_WRITE"); sandboxRewrite != "" {
+			builder.updateEnv("SANDBOX_WRITE=" + sandboxRewrite + ":" + ccacheDir)
+		}
+
+		// Make sure we keep the cached files group writable.
+		builder.updateEnv("CCACHE_DIR="+ccacheDir, "CCACHE_UMASK=002")
+
+		// ccache may generate false positive warnings.
+		// Workaround bug https://crbug.com/649740
+		if builder.target.compilerType == clangType {
+			builder.updateEnv("CCACHE_CPP2=yes")
+		}
+
+		builder.wrapPath("/usr/bin/ccache")
+	}
+}